Well my buddy owns an Infinity I30 and doesn't know much about cars. His car was throwing a CEL and we took it to AutoZone to get the codes.

There was P0150 and P0325 (first code had to do with the 02 Sensor and the second code had to do with the Knock sensor)

I couldn't find any good infinity forums to help me out, so hopefully someone can point him in the right direction.